The American Heart association and the European Society of Cardiology recommend a dietary consumption of polyunsaturated fatty acids (PUFAs) at 1 g/d for the prevention of coronary heart disease. Human dietary sources of PUFAs are mainly derived from fish and fish oil. Unfortunately these natural sources may be compromised with the bioaccumulation of toxins; further the composition of fatty acids (FAs) in the derived oil are not consistent and may not always be high in PUFAs. Sadly declining wild fisheries alone will not fulfill the demand for the dietary requirements from a growing human population. Microalgae are sources of a variety of beneficial metabolites including FAs. They are capable of synthesizing and accumulating PUFAs providing an alternate source for dietary requirements. Oleaginous microalgae are known for their varying lipid productivity and can accumulate up to ~67% lipid by dry wt. Cultivation of microalgae rich in PUFAs is a potential source of dietary omega-3 FAs. In Aim 1 we determine the effect of environmental conditions on PUFA synthesis and primary metabolite pools. We will quantify the abundance and specific FA composition of lipid produced by the oleaginous microalgae N. salina when grown under cold stress & nutrient stress. Adaptability of microalgae to varying environmental conditions does not only directly affect growth and yield but has a determining role on lipid production and composition. In Aim 2 we will determine the complete lipidome by a detailed compositional analysis using FT-ICR MS. These results will identify lipid classes enriched in PUFAs side chains. We will also determine how lipid classes and metabolic pools are influenced and remodeled by abiotic environmental stress promoting the synthesis of PUFAs that are sequestered into triacylglycerol (TAG) synthesis and accumulation. At the conclusion of this pilot proposal, we will have new information on the roles of abiotic stress on total PUFA accumulation and the metabolic reallocation that supports carbon flux towards their synthesis. Secondly we identify the role that other lipid species play in remodeling and providing highly unsaturated FAs to support the de novo synthesis of TAG rich in PUFA. Algae cultivation is well suited to the desert southwest, especially marine algae, which can use the non-arable land and saline aquifers. The cultivation of microalgae rich in PUFAs is a potential source of dietary omega-3 FAs which can be broadly and economically available for the prevention of nutritionally-based health disparities in the southwestern United States.